15. Thalictrum L. (meadow-rue)

Plants perennial herbs, sometimes with rhizomes (these often somewhat woody in Missouri species) or tuberous roots, often dioecious (monoecious elsewhere). Stems erect or ascending. Leaves alternate (opposite or rarely whorled in T. thalictroides) and in a basal rosette, 2–4 times ternately or ternately-pinnately compound, the leaflets obovate to ovate, lanceolate, or kidney-shaped, sometimes with 3 or more lobes. Inflorescences terminal and sometimes also axillary, many-flowered (to 200) racemes or panicles with loose to dense clusters of flowers (reduced to few-flowered umbels or solitary flowers in T. thalictroides). Flowers actinomorphic, perfect or imperfect. Sepals 4–10, white to green, pink, or purple, 2–13 mm long, plane, not persistent at fruiting. Petals absent. Stamens sometimes relatively prominent but not showy, the anthers yellow. Staminodes absent. Pistils (3–)6–21, each with 1 ovule. Style present or absent. Fruits achenes, ellipsoid to narrowly ovoid, sometimes appearing short-stalked, the tip with or without a short beak (when present, this to about 0.5 mm long), the outer wall thick, prominently veined or ribbed. Receptacle not much enlarged at fruiting. About 150 species, nearly worldwide.